Results of Proficiency Test Gasoil (ASTM Spec) September 2016

Transcription

1 Results of Proficiency Test Gasoil (ASTM Spec) September 216 Organised by: Authors: Correctors: Report: Spijkenisse, the Netherlands ing. A.S. Noordman de Neef dr. R.G. Visser & ing. L. Sweere iis16g4astm November 216

2 Spijkenisse, November 216 CONTENTS 1 INTRODUCTION SET UP ACCREDITATION PROTOCOL CONFIDENTIALITY STATEMENT SAMPLES STABILITY OF THE SAMPLES ANALYSES RESULTS STATISTICS GRAPHICS Z-SCORES EVALUATION EVALUATION PER TEST AND PER SAMPLE PERFORMANCE EVALUATION FOR THE GROUP OF LABORATORIES COMPARISON OF THE PROFICIENCY TEST OF SEPTEMBER 216 WITH PREVIOUS PTS Appendices: 1. Data, statistical results and graphic results z-scores for the distillation Number of participants per country Abbreviations and literature page 2 of 97 Gasoil: iis16g4astm

3 Spijkenisse, November INTRODUCTION Since 1994, the institute for Interlaboratory Studies organizes every year proficiency tests for Gasoil. In the annual proficiency testing program of 216/217, it was decided to continue the proficiency test for the testing of Gasoil in accordance with the latest applicable version of ASTM D975 specification. In the main PT, 195 laboratories in 78 different countries did register for participation. In the PT for Cetane Number, 6 laboratories in 31 different countries did register for participation. In the PT for the Total Contamination on Gasoil 72 laboratories in 38 different countries and in the PT for the Oxidation Stability on Gasoil 64 laboratories in 33 different countries did register for participation. In total 28 laboratories did register for participation for the above Gas Oil PTs. See appendix 3 for the number of participants per country of the main round. In this report, the results of the 216 proficiency test are presented and discussed. This report is also electronically available through the iis website 2 SET UP The (iis) in Spijkenisse, the Netherlands, was the organiser of this proficiency test (PT). Sample analyses for fit-for-use and homogeneity testing were subcontracted to an ISO/IEC 1725 accredited laboratory. Dependent on registration it was decided to send ultra low Sulphur (ULS) Gasoil samples for the main round robin labelled #1618; for the Cetane Number round robin ULS Gasoil two types of samples labelled #16181 and Hydrogenated Vegetable Oil (HVO) labelled #16182; for the Total Contamination round robin ULS Gasoil samples labelled #16183 and for the Oxidation Stability round robin ULS Gasoil samples labelled # The HVO sample for the Cetane Number PT is a special sample. This type of fuel is not based on crude oil as common Gasoil but based on Hydrogenated Vegetable Oils. Paraffinic Diesel Fuel like Hydrotreated Vegetable Oil is used more and more as Gasoil or as a blend component in Gasoil. According to specification EN1594:16 the main differences between a paraffinic diesel fuel and automotive diesel fuel are in the areas of Density, Sulfur, Aromatics and Cetane. In order to learn about the testing of properties for Cetane Number of HVO Diesel, it was decided to send an additional sample of HVO Diesel with the Cetane Number Gasoil sample. Participants were requested to report rounded and unrounded test results. The unrounded test results were preferably used for the statistical evaluation. 2.1 ACCREDITATION The in Spijkenisse, the Netherlands, is accredited in agreement with ISO/IEC 1743:21 (R7), since January 2, by the Dutch Accreditation Council (Raad voor Accreditatie). This PT falls under the accredited scope. This ensures strict adherence to protocols for sample preparation and statistical evaluation and 1% confidentiality of participant s data. Feedback from the participants on the reported data is encouraged and customer s satisfaction is measured on regular basis by sending out questionnaires. Gasoil: iis16g4astm page 3 of 97

4 Spijkenisse, November PROTOCOL The protocol followed in the organisation of this proficiency test was the one as described for proficiency testing in the report iis Interlaboratory Studies: Protocol for the Organisation, Statistics and Evaluation of April 214 (iis-protocol, version 3.3). This protocol is electronically available through the iis website from the FAQ page. 2.3 CONFIDENTIALITY STATEMENT All data presented in this report must be regarded as confidential and for use by the participating companies only. Disclosure of the information in this report is only allowed by means of the entire report. Use of the contents of this report for third parties is only allowed by written permission of the. Disclosure of the identity of one or more of the participating companies will be done only after receipt of a written agreement of the companies involved. 2.4 SAMPLES Preparation of samples for PT on regular low sulphur winter Gasoil (main round) From a batch of 8 litre low sulphur Gasoil (automotive diesel), which was purchased from the local market, approx. 35 litre for the regular samples was homogenized in a mixing vessel. Out of this batch, 22 amber glass bottles of 1L and 22 amber glass bottles of.5l, with inner and outer caps were filled and labelled #1618. The homogeneity of the subsamples was checked by the determination of Density in accordance with ASTM D452 on 1 stratified randomly selected samples. Density at 15 C in kg/m 3 Density at 15 C in kg/m 3 sample # sample # sample # sample # sample # sample # sample # sample # sample # sample # Table 1: homogeneity test results of subsamples #1618 From the above test results, the repeatability was calculated and compared with.3 times the corresponding reproducibility of the reference test method in agreement with the procedure of ISO 13528, Annex B2 in the next table: Density at 15 C in kg/m 3 r (observed).3 reference test method ASTM D452:15.3*R (reference test method).16 Table 2: evaluation of the repeatability of subsamples #1618 The calculated repeatability was less than.3 times the reproducibility of the reference test method. Therefore, homogeneity of the subsamples #1618 was assumed. page 4 of 97 Gasoil: iis16g4astm

5 Spijkenisse, November 216 Preparation of samples for PT on Cetane Number in Gasoil and in hydrogenated vegetable oil From the batch of 8 litre for the main round, another 3 litre was homogenized in the mixing vessel and 26 amber glass bottles of 1L with inner and outer caps were filled and labelled # A batch of 3 litre hydrogenated vegetable oil was obtained from a third party. This batch was homogenized in the mixing vessel and 26 amber glass bottles of 1L with inner and outer caps were filled and labelled # The homogeneities of the subsamples of #16181 and #18182 were checked by the determination of Density in accordance with ASTM D452 on 8 stratified randomly selected samples of #16181 and of # Density at 15 C in kg/m 3 sample #16181 Density at 15 C in kg/m 3 sample #16182 sample sample sample sample sample sample sample sample Table 3: homogeneity test results of subsamples #16181 and #16182 From the above test results, the repeatabilities were calculated and compared with.3 times the corresponding reproducibility of the reference test method in agreement with the procedure of ISO 13528, Annex B2 in the next table: Density at 15 C in kg/m 3 sample #16181 Density at 15 C in kg/m 3 sample #16182 r (observed).2.3 reference test method ASTM D452:15 ASTM D452:15.3*R (reference test method) Table 4: precision data of the subsamples #16181 The calculated repeatabilities were less than.3 times the reproducibility of the reference test method. Therefore, homogeneity of the subsamples #16181 or #16182 was assumed. Gasoil: iis16g4astm page 5 of 97

6 Spijkenisse, November 216 Preparation of samples for PT on Total Contamination in Gasoil The remaining material (approx. 85 litre) of the low sulphur Gasoil batch used for the main round was homogenized again and 8 amber glass bottles of 1L with inner and outer caps were filled and labelled # Each of the 8 filled bottles was spiked with 1 ml of a freshly prepared and ultrasonically homogenized, 1 g/kg particulate quartz material BCR-67 (ø µm) in oil suspention. The addition was checked by weighting each bottle before and after addition of the spike. Preparation of samples for PT on Oxidation Stability in Gasoil For the Oxidation Stability determination 58 litre of another batch of regular Gasoil obtained at a local supplier was homogenised and subsequently divided over 78 amber glass bottles of.5l with inner and outer caps and labelled # The homogeneity of the subsamples was checked by the determination of Density in accordance with ASTM D452 on 8 stratified randomly selected samples. Density at 15 C in kg/m 3 Density at 15 C in kg/m 3 sample # sample # sample # sample # sample # sample # sample # sample # Table 5: homogeneity test results of subsamples #16184 From the above test results the repeatability was calculated and compared with.3 times the corresponding reproducibility of the reference test method in agreement with the procedure of ISO 13528, Annex B2 in the next table: Density at 15 C in kg/m 3 r (observed).1 reference test method ASTM D452:15.3*R (reference test method).16 Table 6: precision data of the subsamples #16184 The calculated repeatability was less than.3 times the reproducibility of the reference test method. Therefore, homogeneity of the subsamples #16184 was assumed. Depending on the registration of the participant: one bottle of 1L #1618 and one bottle of.5l #1618, four bottles of 1L #16181, three bottles of 1L #16182, one bottle of 1L #16183 and/or 1 bottle of.5l #16184 were sent to the participating laboratories on August 31, STABILITY OF THE SAMPLES The stability of the ultra low Sulphur Gasoil packed in amber glass bottles was checked. The material was found sufficiently stable for the period of the proficiency test. page 6 of 97 Gasoil: iis16g4astm

7 Spijkenisse, November ANALYSES The participants were requested to determine on the samples of #1618; Acid number (total), Aromatics by FIA, Ash Content, Calculated Cetane Index (D976 and D4737), Cloud Point, Cold Filter Plugging Point (CFPP), Color ASTM, Conradson Carbon Residue, Ramsbottom Carbon Residue, Copper Corrosion, Density at 15 C, Distillation (IBP, 1%, 5%, 9%, 95% recovered, FBP and %V/V at 25 C and 35 C), FAME content, Flash Point PMcc, Kinematic Viscosity at 4 C, Lubricity by HFRR, Nitrogen, Pour Point (manual and/or automated), Sulphur content, Water content and Water & Sediment (D279 & D1796). On samples #16181 and #16182 were requested to determine; Cetane number, Derived Cetane number (D689 and D7668), Iginiton Delay (D689 and D7668), Air temperature, Combustion Delay and Chamber Wall Temperature. On sample #16183 was requested to determine; Total Contamination and on sample #16184; Oxidation Stability (Filterable Insolubles, Adherent Insolubles and Total Insolubles) was requested to determine. To get comparable test results a detailed report form, on which the units were prescribed as well as the required reference test method and a letter of instructions were prepared and made available on the data entry portal The laboratories were also requested to confirm the sample receipt on the same data entry portal. A SDS was added to the samples. 3 RESULTS During five weeks after sample dispatch, the test results of the individual laboratories were gathered via the data entry portal The reported test results are tabulated per determination in appendix 1 of this report. The laboratories are presented by their code numbers. Directly after the deadline, a reminder was sent to those laboratories that had not reported test results at that moment. Shortly after the deadline, the available test results were screened for suspect data. A test result was called suspect in case the Huber Elimination Rule (a robust outlier test) found it to be an outlier. The laboratories that produced these suspect data were asked to check the reported test results (no reanalysis). Additional or corrected test results are used for data analysis and original test results are placed under 'Remarks' in the test result tables in appendix 1. Test results that came in after the deadline were not taken into account in this screening for suspect data and thus these participants were not requested for checks. 3.1 STATISTICS The protocol followed in the organization of this proficiency test was the one as described for proficiency testing in the report iis Interlaboratory Studies: Protocol for the Organisation, Statistics and Evaluation of April 214 (iis-protocol, version 3.3). For the statistical evaluation the unrounded (when available) figures were used instead of the rounded test results. Test results reported as < or > were not used in the statistical evaluation. Gasoil: iis16g4astm page 7 of 97

8 Spijkenisse, November 216 First, the normality of the distribution of the various data sets per determination was checked by means of the Lilliefors-test a variant of the Kolmogorov-Smirnov test and by the calculation of skewness and kurtosis. Evaluation of the three normality indicators in combination with the visual evaluation of the graphic Kernel density plot, lead to judgement of the normality being either unknown, OK, suspect or not OK. After removal of outliers, this check was repeated. Not all data sets proved to have a normal distribution, in which cases the statistical evaluation of the test results should be used with due care. According to ISO 5725 the original test results per determination were submitted to Dixon s, Grubbs and/or Rosner s outlier tests. Outliers are marked by D(.1) for the Dixon s test, by G(.1) or DG(.1) for the Grubbs test and by R(.1) for the Rosner s test. Stragglers are marked by D(.5) for the Dixon s test, by G(.5) or DG(.5) for the Grubbs test and by R(.5) for the Rosner s test. Both outliers and stragglers were not included in the calculations of averages and standard deviations. For each assigned value the uncertainty was determined in accordance with ISO Subsequently the calculated uncertainty was evaluated against the respective requirement based on the target reproducibility in accordance with ISO When the uncertainty passed the evaluation, no remarks are made in the report. However, when the uncertainty failed the evaluation it is mentioned in the report and it will have consequences for the evaluation of the test results. Finally, the reproducibilities were calculated from the standard deviations by multiplying them with a factor of GRAPHICS In order to visualise the data against the reproducibilities from literature, Gauss plots were made, using the sorted data for one determination (see appendix 1). On the Y-axis the reported test results are plotted. The corresponding laboratory numbers are on the X-axis. The straight horizontal line presents the consensus value (a trimmed mean). The four striped lines, parallel to the consensus value line, are the +3s, +2s, -2s and -3s target reproducibility limits of the selected reference test method. Outliers and other data, which were excluded from the calculations, are represented as a cross. Accepted data are represented as a triangle. Furthermore, Kernel Density Graphs were made. This is a method for producing a smooth density approximation to a set of data that avoids some problems associated with histograms. Also a normal Gauss curve was projected over the Kernel Density Graph for reference. 3.3 Z-SCORES To evaluate the performance of the participating laboratories the z-scores were calculated. As it was decided to evaluate the performance of the participants in this proficiency test (PT) against the literature requirements, e.g. ASTM reproducibilities, the z-scores were calculated using a target standard deviation. This results in an evaluation independent of the variation of this interlaboratory study. The target standard deviation was calculated from the literature reproducibility by division with 2.8. page 8 of 97 Gasoil: iis16g4astm

9 Spijkenisse, November 216 When a laboratory did use a test method with a reproducibility that is significantly different from the reproducibility of the reference test method used in this report, it is strongly advised to recalculate the z-score, while using the reproducibility of the actual test method used, this in order to evaluate whether the reported test result is fit-for-use. The z-scores were calculated according to: z (target) = (test result - average of PT) / target standard deviation The z (target) scores are listed in the test result tables in appendix 1. Absolute values for z<2 are very common and absolute values for z>3 are very rare. The usual interpretation of z-scores is as follows: z < 1 good 1 < z < 2 satisfactory 2 < z < 3 questionable 3 < z unsatisfactory 4 EVALUATION In this interlaboratory study, a number of laboratories encountered problems with sample despatch. For the main PT: nine participants reported test results after the final reporting date and nine participants did not report any test results at all. For the PT on Cetane Number: three participants reported the test results after the final reporting date and five participants did not report any test results at all. For the PT on Total Contamination: five participants reported the test results after the final reporting date and four participants did not report any test results at all. For the Oxidation Stability PT: four participants reported the test results after the final reporting date and eight participants did not report any test results at all. Finally, 199 participants reported in total 3721 numerical test results. Observed were 61 outlying test results, which is 1.6%. In proficiency studies, outlier percentages of 3% - 7.5% are quite normal. In the iis PT reports, ASTM test methods are referred to with a number (e.g. D976) and an added designation for the year that the test method was adopted or revised (e.g. D976:6). If applicable, a designation in parentheses is added to designate the year of reapproval (e.g. D976:6 (216)). In the test results tables of Appendix 1 only the test method number and year of adoption will be used. The abbreviations, used in these tables, are listed in appendix 4. Not all original data sets proved to have a normal Gaussian distribution. These are referred to as not OK or suspect. The statistical evaluation of these data sets should be used with due care. Gasoil: iis16g4astm page 9 of 97

10 Spijkenisse, November EVALUATION PER TEST AND PER SAMPLE In this section, the results are discussed per sample and per test. The specified test methods and requirements were taken into account for explaining the observed differences when possible and applicable. These test methods are also in the tables together with the reported data. Acid Number (Total): This determination was not problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outlier is in good agreement with the requirements of ASTM D974:14e2. Aromatics (FIA): This determination was problematic. Two statistical outliers were observed and one test result was excluded as this test result was reported in %M/M. The calculated reproducibility after rejection of the suspect data is not in agreement with the requirements of ASTM D1319:15. One should be aware that this Gasoil does not meet the scope of ASTM D1319 (petroleum fractions should be distilling below 315 C). Another explanation for the large observed reproducibility might be that more participants than one may have reported a test result in %M/M. Ash: C.I. D976: C.I. D4737: Regretfully, the ash content for this sample was near or below the application range of the test method. Therefore, no z-scores were calculated. Nevertheless, two statistical outliers were observed. This determination was not problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outlier is in good agreement with the requirements of ASTM D976:6(216) and ASTM D976:8(199)e1. The specification for Gas Oil ASTM D975:16 table 1 refers to the version from 198. Eight participants probably made calculation errors. This determination might not to be problematic compared to the calculated reproducibility of iis15g4astm. Regretfully, no reproducibility is mentioned in ASTM D4737:1(216). No statistical outliers were observed. Not all participants used procedure A for the calculation of C.I. as mentioned in the scope of ASTM D4737 for this type of Gasoil. Eight participants reported and calculated the C.I. according to ASTM D4737 procedure B and therefore these test results were excluded. One participant reported to use procedure B for the calculation but the test result appeared to be calculated by procedure A. Therefore, this test result was not excluded. Eight participants possibly made a calculation error. Up to 23 ISO4264/IP38 and ASTM D4737 were equivalent test methods and the calculation formula mentioned is the same as given in procedure A. page 1 of 97 Gasoil: iis16g4astm

11 Spijkenisse, November 216 Cloud Point: CFPP: Colour ASTM: This determination was not problematic. Two statistical outliers were observed. However, the calculated reproducibility after rejection of the statistical outliers is in good agreement with the requirements of ASTM D25:16a. This determination was problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outlier is not in agreement with the requirements of ASTM D6371:5(21). This determination was not problematic. Four statistical outliers were observed. However, the calculated reproducibility after rejection of the statistical outliers is in good agreement with the requirements of ASTM D15:12. Conradson CR: This determination was not problematic. No statistical outliers were observed. The calculated reproducibility is in full agreement with the requirements of ASTM D189:6(214). Ramsbottom CR: This determination was problematic. No statistical outliers were observed. However, the calculated reproducibility is not in agreement with the requirements of ASTM D524:15. Copper Corrosion: This determination was not problematic. All participants agreed on a result of 1 (or 1A or 1B). Density at 15 C: This determination was not problematic. Three statistical outliers were observed. However, the calculated reproducibility after rejection of the statistical outliers is in agreement with the requirements of ASTM D452:15. Distillation: FAME: This determination was not problematic. In total twelve statistical outliers were observed and four test results, all reported by the same participant, were excluded. All calculated reproducibilities after rejection of the suspect data are in agreement with the requirements of ASTM D86:16a (automated). When evaluated against ASTM D86:16a (manual) the calculated reproducibilities of IBP, 95% rec and FBP after rejection of the suspect data are not in agreement with the requirements of the manual test method. This determination was not problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outlier is in good agreement with the requirements of ASTM D7371:14. It is remarkable that most laboratories reported test method EN1478, which is not mentioned in Gas Oil specification ASTM D975:16. However, in Gas Oil specification ASTM D7467:15ce1, paragraph it is mentioned that EN1478 may be used instead of ASTM D7371. It should be noted that the calculated reproducibility is not at all in agreement with the more strictly requirements of EN1478:14; range B. Gasoil: iis16g4astm page 11 of 97

12 Spijkenisse, November 216 Flash Point: This determination was not problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outlier is in full agreement with the requirements of ASTM D93:15 (procedure A). Kinematic. Visc. 4 C: This determination was problematic. Eight (!) statistical outliers were observed. The calculated reproducibility after rejection of the statistical outliers is not in agreement with the requirements of ASTM D445:15a. Lubricity: Nitrogen: Pour Point: Sulphur: Water: This determination was problematic. No statistical outliers were observed. The calculated reproducibility is not in agreement with the requirements of ASTM D679:11(216). When the calculated reproducibilities for ASTM D679 and for ISO12156 (equal to ASTM D7688/IP45) were evaluated separately, both observed reproducibilities are not in agreement with the requirements of the respective test methods. There reason may be that not all laboratories may use a climatic chamber as required. This determination was problematic. Two statistical outliers were observed. The calculated reproducibility after rejection of the statistical outliers is not in agreement with the requirements of ASTM D4629:12. The determination was not problematic for the manual mode. No statistical outliers were observed and the calculated reproducibility is in good agreement with the requirements of ASTM D97:16. Also for the automated mode the determination was not problematic. Two statistical outliers were observed. However, the calculated reproducibility after rejection of the statistical outliers is in good agreement with the requirements of ASTM D595:14. This determination was not problematic. One statistical outlier was observed. The calculated reproducibility after rejection of the statistical outliers is in full agreement with the requirements of ASTM D5453:16e1. This determination was not problematic. One statistical outlier was observed and one test result excluded. The calculated reproducibility after rejection of the suspect data is in good agreement with the requirements of the ASTM D634-A:16e1. Water and Sediment (D279): Most reporting laboratories reported a less than test result or zero. Therefore no significant conclusions were drawn. Water and Sediment (D1796): Most reporting laboratories reported a less than test result or zero. Therefore no significant conclusions were drawn. page 12 of 97 Gasoil: iis16g4astm

13 Spijkenisse, November 216 CN - D613: DCN - D689: This determination was not problematic for sample #16181 and for sample #16182 (HVO). No statistical outliers were observed. The calculated reproducibilities are in agreement with the requirements of ASTM D613:16e1. Allthough the CN for the HVO sample (#16182) is above the application limits of the target reproducibility of ASTM D613:16e1 the calculated reproducibility for CN seems very well in agreement with the requirements of ASTM D613:16e1. Therefore, the z-scores are also calculated for sample # This determination was not problematic for sample # No statistical outliers were observed. The calculated reproducibilities for DCN and for ID are in agreement with the requirements of ASTM D689:16. No calculation errors were observed. The DCN determination was problematic for sample #16182 (HVO). No statistical outliers were observed. Three test results were excluded because the formula were used for ID range ms. Test method EN 15195:15 mentioned in Annex D to use another formula when ID is outside the range of ms. Test method ASTM D689 mentions also to the same formula as in EN when the ID is outside the range of ms. Further, no calculation errors were observed. Allthough the ID is outside the application limits of the target reproducibilities of ASTM D689:16 the calculated reproducibility for ID is in agreement with the requirements of ASTM D689:16. Therefore, the z-scores are calculated for DCN and ID. However, the calculated reproducibility for DCN after rejection of suspect data is not in agreement with the requirements of ASTM D689:16. DCN - D7668: This determination was problematic for sample # In total, two statistical outliers were observed. Three test results were excluded as iis could not reproduce the calculation of DCN or the reported value for CD seems not correct. The calculated reproducibility for DCN after rejection of suspect data is not in agreement with the requirements of ASTM D7668:14a. The calculated reproducibility for ID after rejection of the statistical outliers is in full agreement with the requirements of ASTM D7668:14a. The calculated reproducibility for CD after rejection of suspect data is almost in agreement with the requirements of ASTM D7668:14a. Please note that the requirements of ASTM D7668:14a are stricter than the requirements of ASTM D689:16 at the same level of DCN while the calculated reproducibilities of both test methods in this PT are equal. This determination was also problematic for sample #16182 (HVO). No statistical outliers were observed. However, the calculated reproducibilities for DCN, ID and CD are not in agreement with the requirements of ASTM D7668:14a. Three participants may have made a calculation error for the DCN. Gasoil: iis16g4astm page 13 of 97

14 Spijkenisse, November 216 Total Contamination: This proficiency test was set-up according to specification ASTM D975 for Gas Oil and therefore it was expected that test method ASTM D6217 would be the reported test method for the determination of Total Contamintion in Gas Oil. Suprisenly, many participants reported test method EN Major differences between ASTM D6217 and test method EN12662 are the volumes used for testing and the reporting unit (mg/l vs mg/kg). Therefore, the reported test results were split up into two groups; one that reported in mg/l and one that reported in mg/kg. As the majority of the mg/kg group reported test method EN12662, it was decided to use the precision data of EN12662:14 for the group reported in mg/kg and for the group reported in mg/l to use the precision data of ASTM D6217:11. Seven participants that had reported a test method not in line with the reported unit were asked for more background. It appeared that two laboratories had converted the determined value, one had reported the wrong test method and four had reported the wrong unit. The last five were placed in the corresponding table based on the feedback. The samples of 1 litre were spiked with 1 ml of a freshly prepared and ultrasonically homogenized, 1 g/kg particulate quartz material BCR-67 (ø µm) in oil suspention. Therefore, the expected test result should be higher than 1 mg/l (or 13 mg/kg). Lower reported test values were excluded. The determination in mg/l was problematic. One statistical outlier was observed. This laboratory used ASTM D4898 which is intended for Hydraulic Fluids. Two test results were excluded as the reporting laboratories did not report at least the spiked amount. The calculated reproducibility after rejection of the suspect data is not in agreement with the requirements of ASTM D6217:11. The determination in mg/kg was not problematic. Two statistical outliers were observed. Six test results were excluded, as the reporting laboratories did not report at least the spiked amount. The calculated reproducibility after rejection of the suspect data is in agreement with the requirements of EN12662:14. Oxidation Stability: Filterable Insolubles (A) This determination was not problematic at this low level of.12 mg/1ml. Four statistical outliers were observed. One test result was excluded because this participant reported a negative test result, which indicates the use of an incorrect procedure. However, the calculated reproducibility after rejection of the suspect data might be in full agreement with ASTM D2274:14. Adherent Insolubles Insolubles (B) This determination was not problematic at this low level of.15 mg/1ml. Three statistical outliers were observed. One test result was excluded (see Filterable Insolubles (A)). The calculated reproducibility after rejection of the suspect data is in full agreement with ASTM D2274:14. page 14 of 97 Gasoil: iis16g4astm

15 Spijkenisse, November 216 Total Insolubles This determination was not problematic at this low level of.27 mg/1ml. Five statistical outliers were observed. One test result was excluded (see Filterable Insolubles (A)). The calculated reproducibility after rejection of the suspect data is in agreement with ASTM D2274: PERFORMANCE EVALUATION FOR THE GROUP OF LABORATORIES A comparison has been made between the reproducibility as declared by the relevant reference test method and the reproducibility as found for the group of laboratories that participated. The average results of the evaluated parameters, calculated reproducibilities and reproducibilities, derived from literature test methods (in casu ASTM test methods) are compared in the next tables. Parameter unit n average 2.8 * sd R (lit) Acid Number (Total) mgkoh/g Aromatics by FIA %V/V Ash content %M/M (.5) Cetane Index ASTM D Cetane Index ASTM D n.a. Cloud Point C Cold Filter Plugging Point C Colour ASTM Conradson Carbon Residue %M/M Ramsbottom Carbon Residue %M/M Copper Corrosion 3hrs at 5 C 139 1(1A/1B) n.a. n.a. Density at 15 C kg/m Distillation Auto Manual -IBP C % recovery C % recovery C % recovery C % recovery C FBP C Volume at 25 C %V/V Volume at 35 C %V/V FAME %V/V Flash Point PMcc C Kinematic Viscosity at 4 C mm 2 /s Lubricity by HFRR µm Nitrogen mg/kg Pour Point, manual C Pour Point, automated C Sulphur mg/kg Water mg/kg Water and Sediment (D279) %V/V 53 <.5 n.a. n.a. Water and Sediment (D1796) %V/V 38 <.5 n.a. n.a. Table 7: reproducibility of tests on sample #1618. NB: results between brackets may be near or below the limit of detection Gasoil: iis16g4astm page 15 of 97

16 Spijkenisse, November 216 Parameters unit n average 2.8 * sd R (lit) Cetane Number DCN (D689) Iginition delay (D689) DCN (D7668) Ignition delay (D7668) Combustion delay (D7668) Table 8: reproducibility of tests on sample #16181 Parameters unit n average 2.8 * sd R (lit) Cetane Number DCN (D689) Iginition delay (D689) DCN (D7668) Ignition delay (D7668) Combustion delay (D7668) Table 9: reproducibility of tests on sample #16182 Parameters unit n average 2.8 * sd R (lit) Total Contamination mg/l Total Contamination mg/kg Table 1: reproducibility of tests on sample #16183 Parameters unit n average 2.8 * sd R (lit) Oxidation Stab. Filt. Insol. A mg/1ml Oxidation Stab. Adher. Insol B mg/1ml Oxidation Stab. Tot. Insol. mg/1ml Table 11: reproducibility of tests on sample #16184 Without further statistical calculations, it can be concluded that for several tests there is a good compliance of the group of participating laboratories with the relevant reference test methods. The problematic tests have been discussed in paragraph COMPARISON OF THE INTERLABORATORY STUDY OF SEPTEMBER 216 WITH PREVIOUS PTS. Sept 216 Sept 215 Sept 214 Sept 213 Oct 212 Number of reporting labs Number of test results reported Statistical outliers Percentage outliers 1.6% 1.8% 2.% 2.1% 3.1% Table 12: comparison with previous proficiency tests. In proficiency tests, outlier percentages of 3% - 7.5% are quite normal. page 16 of 97 Gasoil: iis16g4astm

17 Spijkenisse, November 216 The performance of the determinations of the proficiency tests was compared against the requirements of the respective reference test methods. The conclusions are given the following table: Parameter Sept 216 Sept 215 Sept 214 Sept 213 Oct 212 Acid Number (Total) Aromatics by FIA Ash content (++) (++) (++) (++) (++) Cetane Index ASTM D n.e. n.e. n.e. Cloud Point Cold Filter Plugging Point Colour ASTM Conradson Carbon Residue + +/ /- Ramsbottom Carbon R id Density at 15 C Distillation FAME (++) Flash Point PMcc +/ Kinematic Viscosity at 4 C - +/ Lubricity by HFRR Nitrogen Pour Point (manual and auto) Sulphur /- + Water Cetane Number DCN (D689) +/- +/ Ignition Delay (D689) + +/ DCN (D7668) - +/- -- n.e. n.e. Ignition Delay (D7668) +/- +/- -- n.e. n.e. Combustion Delay (D7668) - - n.e. n.e. n.e. Total Contamination mg/l - -- n.e. n.e. n.e. Total Contamination mg/kg +/ n.e. Oxidation Stab. Filt. Insol. A +/- +/ Oxidation Stab. Ad. Insol. B +/- +/- n.e. n.e. n.e. Oxidation Stab. Total Insol. + + n.e. n.e. n.e. Table 13: comparison determinations against the refence test method The performance of the determinations against the requirements of the respective reference test methods is listed in the above table. The following performance categories were used: ++: group performed much better than the reference test method + : group performed better than the reference test method +/-: group performance similar to the reference test method - : group performed worse than the reference test method -- : group performed much worse than the reference test method n.e.: not evaluated Gasoil: iis16g4astm page 17 of 97

18 Spijkenisse, November 216 APPENDIX 1 Determination of Acid Number (total) on sample #1618; results in mgkoh/g lab method value mark z(targ) lab method value mark z(targ) 52 D664-A < D664-A D664-A D664-A < D664-A D664-A D664-A < D664-A D664-A < D664-A D664-A D664-A < D664-A D664-A D664-A D664-A < D D664-A D664-A D664-A D D D664-A D D664-A D974.6 R(.1) D D664-A D664-A D664-A < D D D ISO D D ISO6619 <, D D D D664-A D D D D D D IP D664-A D664-A D664-A D664-A <, D664-A D D664-A D D664-A D664-A D664-A D664-A D D664-A D664-A D664-A D664-A D664-A D974 < D664-A D664-A D664-A D664-A < D664-A D664-A IP D664-A D664-A D664-A.5 C D D664-A D D664-A ISO D D664-A D664-A D D664-A D664-A page 18 of 97 Gasoil: iis16g4astm

19 Spijkenisse, November 216 lab method value mark z(targ) lab method value mark z(targ) 1643 D664-A D664-A D664-A D664-A D D664-A <, D664-A D664-A D664-A D664-A D D D664-A D D664-A D D664-A ISO D664-A normality suspect n 95 outliers 1 mean (n).228 st.dev. (n).888 R(calc.).249 R(D974:14e2).4 compare R(D664:11ae1-A) =.1442 Lab 634 first reported: Kernel Density Gasoil: iis16g4astm page 19 of 97

20 Spijkenisse, November 216 Determination of Aromatics by FIA on sample #1618; results in %V/V lab method value mark z(targ) lab method value mark z(targ) D D D D D D D D D C D D D D D D D D D D D D D D D D D D D D D D IP ex D page 2 of 97 Gasoil: iis16g4astm

21 Spijkenisse, November 216 lab method value mark z(targ) lab method value mark z(targ) D R(.1) D D EN R(.1) normality OK n 35 outliers 2+1ex mean (n) st.dev. (n) R(calc.) 4.98 R(D1319:15) 3.7 Lab 15 first reported: 16.6 Lab 1613 excluded, reported test result in %M/M Kernel Density Gasoil: iis16g4astm page 21 of 97

22 Spijkenisse, November 216 Determination of Ash on sample #1618; results in %M/M lab method value mark z(targ) lab method value mark z(targ) 52 D482 < D D D D482 < D482 < D482 < D482 < ISO6245 < D D D482 < D D482 < D482 < D D D D482 < D482 < D482 < D D D D D D D D482 < D D D D D482 < D ISO D D D D482 < D D D ISO6245 <, D D482 < D R(.1), f+? D482 < D482 < D D482 < D IP4 < IP D ISO ISO D482 <.1 C ISO D ISO IP D482 < D D D482 < ISO D IP4 < ISO D R(.1), f+? ISO D482 < D D D D ISO D482 < D GOST D D D D D482 < ISO D D D D D D D D ISO D D482 < D D D D page 22 of 97 Gasoil: iis16g4astm

23 Spijkenisse, November 216 lab method value mark z(targ) lab method value mark z(targ) 1643 D ISO D ISO ISO D D ISO D D482 < D ISO D482 < D ISO ISO ISO ISO ISO normality not OK n 88 outliers 2 mean (n).82 st.dev. (n).614 R(calc.).172 R(D482:13) (.5) Application range:.1.18 %M/M Lab 343 first reported: Kernel Density Gasoil: iis16g4astm page 23 of 97